The present invention relates generally to wall structures and in particular to log wall structures.
Log construction has been known for many decades as typified by the log cabin. For many years the logs have been notched so that at a corner, logs forming one wall of a structure can be laid on top of and at an angle alternating with logs from an intersecting wall. Although a number of materials may be used to form the “logs” used as wall members, including various types of composite materials, the wall members are typically milled from wood. The term “logs” will be used throughout this disclosure to include all types of materials that simulate a horizontal wooden log and includes different cross sections, either machined, hand-hewn or in a natural state.
The assembly of buildings from logs has been performed using traditional techniques. Where hand hewn logs are used, the builder individually fits each log to ensure a proper fit. Whilst this is traditionally done at the final site of the building it has become more common to assemble the shell of the building at a convenient remote location and then disassemble the logs for transportation. The building is then reassembled at the intended site and finished.
Log buildings using manufactured logs have the logs machined and cut at the factory to provide the desired floor plan. The logs are then transported to the site where the building is assembled.
In practical use, traditional construction is usually limited to right angle corners because of the complexity of the angled notches required for non-right angle corners. More recently, posts have been introduced that can be milled with longitudinal faces at a range of desirable angles such that wall members having square-cut ends can be attached by spikes to the posts to form right-angle or non-right angle corners.
To form a tight connection between the logs and the posts, split key members have been used that engage cooperating undercut recesses in the end of the log and a face of the post. In U.S. Pat. No. 6,050,033 there is disclosed a spline arrangement in which the log and post are connected by a key formed by a pair of wedges. The key is expandable and secures the log to the post. A first section of the key member is fitted into place to engage the recesses in the post and the log and then a second section of the key member is inserted and tapped into place beside the first section of the key member. The cross-sections of the split key member are wedge-shaped and tighten the joint as the second portion of the key member is tapped into place.
It is necessary to ensure that the interconnecting butt joints are tight and provide an effective seal, but at the same time accommodate relative movement between logs whilst maintaining the seal. This is particularly an issue in wooden log construction because of the shrinkage of the logs as they dry. This causes the logs to settle and move vertically down. However, in some circumstances the connection of the key to both the log and the post as shown in U.S. Pat. No. 6,050,033 may inhibit such movement and as a result a gap is created between adjacent logs in the log walls.
Similar considerations apply where a pair of walls intersect, such as where an internal wall meets an external wall. This may occur between the locations of the posts and a secure butt joint between the intersecting walls is required.
It is an object of the present invention to obviate or mitigate the above disadvantages.